An electrically energized soft contact lens disinfecting unit is described and claimed in Copending Application Ser. No. 448,281 which was filed Dec. 9, 1982 in the name of the present inventor and Stephen Hauser, and which issued July 16, 1985 as U.S. Pat. No. 4,529,868 . The unit of the Copending Application will be described herein as an example of a typical soft contact lens disinfecting unit which may incorporate the teachings of the present invention so as to be immune from surfactant contamination.
The Copending Application discloses an electrically energized soft lens disinfecting unit which is compact in size in that the unit itself forms a holder for the lenses having separated compartments for the left and right lenses which are adapted to be filled with an appropriate saline solution, the solution in the compartments being heated by electrical heating elements within the unit to perform the desired disinfecting functions. The unit is equipped with a electric plug which may be directly inserted into an electric receptacle to energize the heating elements.
The soft lens disinfecting unit described in the Copending Application achieved widespread commercial success. However, it was found that some of the units developed leaks after a period of use, and for a long time, the reason for the leaks could not be determined. It was finally found, however, that the leaks were due to contamination of the plastic material from which the unit was formed from certain surfactants used in the manufacture of certain brands of detergents on the market to be used for cleaning soft contact lenses.
Accordingly, the principal objective of the present invention is to provide an electrically energized soft contact lens disinfecting unit which is constructed of a surfactant- resistant plastic material so as to be immune from contamination and resulting leakage regardless of the type of detergent used to clean the lenses to be disinfected by the unit.
As discussed in the Copending Application, previously, hard contact lenses were the only type available, and while such lenses required cleaning, disinfection was not a particular problem. Soft contact lenses, on the other hand, are made from a porous plastic material which absorbs water and, upon doing so, becomes soft and pliable. While hard contact lenses must be cleaned and disinfected on a periodic basis, the soft contact lenses must be disinfected more or less on a daily basis, because the porous nature of the plastic material provides an ideal medium for bacteria.
Accordingly, the soft contact lenses must be cleaned, usually by a detergent sold for the particular purpose, and disinfected in a disinfecting unit on a regular basis, preferably daily. As described above, the present invention has resulted from a finding that some brands of detergent used for cleaning the soft contact lenses cause contamination of the plastic of the disinfecting unit with resulting leakage.
The soft contact lenses may be disinfected by cleaning the lenses with an appropriate detergent, and then by placing the lenses in a saline solution and heating the saline solution to a temperature sufficiently high to destroy any bacteria which might be present in the lenses. One such unit for disinfecting soft contact lenses is described in Copending Application Ser. No. 448,281, as mentioned above. Another type of soft lense disinfecting unit is described in U.S. Pat. No. 4,158,126. The concept of the present invention may be used in conjunction with the soft lens disinfecting units described in the Copending Application and in U.S. Pat. No. 4,158,126, so as to render the unit impervious to surfactant attack, so that the units are capable of long term use without leakage regardless of the brand of detergent used for cleaning the lenses disinfected by the units.